Gamasutra has a postmortem on the rise and fall of KAOS Studios, the developer formed by the team that created the Desert Combat modification for Battlefield 1942. An interesting element of the story is how the studios expansion resulted in hiring developers with more complete resumes than the managers they were working for and other hurdles they had to overcome to succeed in an increasingly competitive FPS genre.

Zynga is the epitome of F2P. Every F2P, which does NOT suck is the big exception which confirms the rule: F2P game are horrible time sinks to force the player into buying shortcuts. Thats the basic principle of the business model F2P, which most F2P games follow.

Your view of F2P is pretty outdated. Yes, Zynga's "games" are technically F2P. They are also Facebook games. That's a pretty important distinction. With real games like Tribes: Ascend, Blacklight: Retribution, LoL, HoN, DotA2, Planetside 2, Firefall, End of Nations, Hawken, Mechwarrior Online, Warface, Warframe, etc, the bar for F2P games is quickly rising. Sure, there will always be lousy cash grabs like Lords of Ultima or that crappy C&C game. However, lousy cash grabs exist in the non-F2P market as well.

There is nothing in the F2P model that requires a game to be a grind. Keep in mind that if a game has strong core gameplay and good balancing, the act of playing it does not constitute grinding, even if there's leveling and unlockables. Grinding is when you perform tedious and mundane actions repeatedly in order to obtain a reward that's otherwise unrelated to the actions you are performing. If you enjoy the gameplay, it's not grinding because playing the game is reward in and of itself.

It all comes down to implementation. Unlockables don't have to be shortcuts. They can be purely aesthetic items to help players stand out. See TF2's hat economy for a good example of this. XP boosts are another popular microtransaction, but that's mainly due to people being impatient. If you enjoy playing a game, you'll play it on a frequent basis and will unlock things quickly regardless. XP boosts may give new players a short-term advantage over other new players but in the long term, that advantage is void because everyone has already unlocked everything they want to. If the unlockables are well-balanced, competing against players with more unlockables should still come down to player skill rather than gear.